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<h1>Developers Manual</h1>
<blockquote>
  <p>This document describes some of Moodle's design and how you can contribute.</p>
  <p>It's a bit thin at the moment - better documentation will come eventually!</p>
  <p>Sections in this document:</p>
  <ol>
    <li><a href="#architecture">Moodle architecture</a></li>
    <li><a href="#contribute">How you can contribute</a> 
      <ul>
        <li><a href="#activities">Learning activities</a></li>
        <li><a href="#themes">Themes</a></li>
        <li><a href="#languages">Languages</a></li>
        <li><a href="#database">Database Schemas</a></li>
        <li><a href="#courseformats">Course formats</a></li>
        <li><a href="#doc">Documentation and articles</a></li>
        <li><a href="#bugs">Participating in the bug tracker</a></li>
      </ul>
    </li>
  </ol>
</blockquote>
<p>&nbsp;</p>
<h2><a name="architecture"></a>1. Moodle architecture</h2>
<blockquote>
  <p>From a system administrator's perspective, Moodle has been designed according 
    to the following criteria:</p>
  <ol>
    <li><strong>Moodle should run on the widest variety of platforms</strong><br />
      <br />
      The web application platform that runs on most platforms is PHP combined 
      with MySQL, and this is the environment that Moodle has been developed in 
      (on Linux, Windows, and Mac OS X). Moodle also uses the ADOdb library for 
      database abstraction, which means Moodle can use <a href="http://php.weblogs.com/ADOdb_manual#drivers">more 
      than ten different brands of database</a> (unfortunately, though, it can 
      not yet <em><strong>set up tables</strong></em> in all these databases - 
      more on this later). <br />
      <br />
    </li>
    <li><strong>Moodle should be easy to install, learn and modify</strong><br />
      <br />
      Early prototypes of Moodle (1999) were built using <a target="_top" href="http://www.zope.org/">Zope</a> 
      - an advanced object-oriented web application server. Unfortunately I found 
      that although the technology was pretty cool, it had a very steep learning 
      curve and was not very flexible in terms of system administration. The PHP 
      scripting language, on the other hand, is very easy to get into (especially 
      if you've done any programming using any other scripting language). Early 
      on I made the decision to avoid using a class-oriented design - again, to 
      keep it simple to understand for novices. Code reuse is instead achieved 
      by libraries of clearly-named functions and consistent layout of script 
      files. PHP is also easy to install (binaries are available for every platform) 
      and is widely available to the point that most web hosting services provide 
      it as standard.<br />
      <br />
    </li>
    <li><strong>It should be easy to upgrade from one version to the next</strong><br />
      <br />
      Moodle knows what version it is (as well as the versions of all plug-in 
      modules) and a mechanism has been built-in so that Moodle can properly upgrade 
      itself to new versions (for example it can rename database tables or add 
      new fields). If using CVS in Unix for example, one can just do a &quot;cvs 
      update -d&quot; and then visit the site home page to complete an upgrade.<br />
      <br />
    </li>
    <li><strong>It should be modular to allow for growth</strong><br />
      <br />
      Moodle has a number of features that are modular, including themes, activities, 
      interface languages, database schemas and course formats. This allows anyone 
      to add features to the main codebase or to even distribute them separately. 
      More on this below in the next section.<br />
      <br />
    </li>
    <li><strong>It should be able to be used in conjunction with other systems</strong><br />
      <br />
      One thing Moodle does is keep all files for one course within a single, 
      normal directory on the server. This would allow a system administrator 
      to provide seamless forms of file-level access for each teacher, such as 
      Appletalk, SMB, NFS, FTP, WebDAV and so on. The authentication modules allow 
      Moodle to use LDAP, IMAP, POP3, NNTP and other databases as sources for 
      user information. Otherwise, there is work yet to do. Features planned for 
      Moodle in future versions include: import and export of Moodle data using 
      XML-based formats (including IMS and SCORM); and increased use of style 
      sheets for interface formatting (so that it can be integrated visually into 
      other web sites).</li>
  </ol>
</blockquote>
<p>&nbsp;</p>
<h2><a name="contribute" id="contribute"></a>2. How you can contribute</h2>
<blockquote>
  <p>As mentioned above, Moodle has a number of features that are modular. Even 
    if you are not a programmer there are things you can change or help with.</p>
  <h3><a name="activities" id="activities"></a>Learning Activities</h3>
  <blockquote>
    <p>These are by far the most important modules, and reside in the 'mod' directory. 
      There are seven default modules: assignment, choice, forum, quiz, 
      resource, and survey. Each module is in a separate subdirectory and consists 
      of the following mandatory elements (plus extra scripts unique to each module):</p>
    <ul>
      <li>mod.html: a form to set up or update an instance of this module</li>
      <li>version.php: defines some meta-info and provides upgrading code</li>
      <li>icon.gif: a 16x16 icon for the module</li>
      <li>db/: SQL dumps of all the required db tables and data (for each database 
        type) </li>
      <li>index.php: a page to list all instances in a course</li>
      <li>view.php: a page to view a particular instance</li>
      <li>lib.php: any/all functions defined by the module should be in here. 
        If the modulename if called widget, then the required functions include: 
        <ul>
          <li>widget_add_instance() - code to add a new instance of widget</li>
          <li>widget_update_instance() - code to update an existing instance</li>
          <li>widget_delete_instance() - code to delete an instance</li>
          <li>widget_user_outline() - given an instance, return a summary of a 
            user's contribution</li>
          <li>widget_user_complete() - given an instance, print details of a user's 
            contribution<br />
          </li>
          <li>To avoid possible conflict, any module functions should be named 
            starting with widget_ and any constants you define should start with 
            WIDGET_ </li>
        </ul>
      </li>
      <li>Lastly, each module will have some language files that contain strings 
        for that module. See below.</li>
    </ul>
    <p>The easiest way to start a new learning activity module is to use the template 
      in <strong><a href="http://moodle.org/mod/newmodule_template.zip">mod/newmodule_template.zip</a>.</strong> 
      Unzip it and follow the README inside. </p>
    <p>You might also like to post first in the <a href="http://moodle.org/mod/forum/view.php?id=44" target="_top">Activities 
      modules forum on Using Moodle</a>.</p>
    <p>&nbsp;</p>
  </blockquote>
  <h3><a name="themes" id="themes"></a>Themes</h3>
  <blockquote>
    <p>Themes (or skins) define the look of a site. A number of simple themes 
      are provided in the main distribution, but you may want to create your own 
      theme with your own colours, logo, styles and graphics. </p>
    <p>Each theme is in a subdirectory of the &quot;theme&quot; directory, and 
      contains at least the following files:</p>
    <ul>
      <li><strong>config.php</strong>: defines the theme colours used throughout 
        the site</li>
      <li><strong>styles.php</strong>: the style sheet, containing CSS definitions 
        for standard HTML elements as well as many Moodle elements.</li>
      <li><strong>header.html</strong>: Included at the top of each page. This 
        is what you need to edit to add a logo at the top of pages, for example.</li>
      <li><strong>footer.html</strong>: Included at the bottom of each page.</li>
    </ul>
    <p>To create your own themes for current versions of Moodle:</p>
    <ol>
      <li>Copy one of the existing theme folders to one with a new name. I recommend 
        starting with one of the standard themes. </li>
      <li>Edit config.php and insert your own colours. </li>
      <li>Edit styles.php and change your CSS styles. </li>
      <li>Edit header.html and footer.html to add new logos, or change the layout. 
      </li>
    </ol>
    <p>Note that all these steps are optional - you can make a radically different 
      look to your site simply by editing the colours in config.php</p>
    <p>Note also that Moodle upgrades <em>may</em> break themes slightly, so check 
      the release notes carefully if you are using a custom theme.</p>
    <p>In particular, Moodle 2.0 will have a completely new display system, probably 
      based on XSL transformations of XML output from Moodle. It is likely that 
      the themes for this will be a completely different format, but the advantage 
      will be a much higher possible degree of customisation (including moving 
      elements around the page).</p>
    <p>More discussion about this in the <a target="_top" href="http://moodle.org/mod/forum/view.php?id=46">Themes 
      forum on Using Moodle</a>. If you create a nice theme that you think others 
      might want to use, please post your zip file on the themes forum!<br />
    </p>
  </blockquote>
  <h3><a name="languages" id="languages"></a>Languages</h3>
  <blockquote>
    <p>Moodle has been designed for internationalisation. Each 'string' or 'page' 
      of text that is displayed as part of the interface is drawn from a set of 
      language files. Each language is a subdirectory of the directory 'lang'. 
      The structure of the lang directory is as follows:</p>
    <p><strong>lang/en</strong> - directory containing all files for one language 
      (eg English)</p>
    <ul>
      <li>moodle.php - strings for main interface</li>
      <li>assignment.php - strings for assignment module</li>
      <li>choice.php - strings for choice module</li>
      <li>forum.php - strings for forum module</li>
      <li>quiz.php - strings for quiz module</li>
      <li>resource.php - strings for resource module</li>
      <li>survey.php - strings for survey module</li>
      <li>.... plus other modules if any.<br />
        <br />
        A string is called from these files using the <strong><em>get_string()</em></strong> or<em> <strong>print_string()</strong> </em>functions. Each string 
        supports variable substitution, to support variable ordering in different 
        languages.<em><br />
        <br />
        </em>eg $strdueby = get_string(&quot;assignmentdueby&quot;, &quot;assignment&quot;, 
        userdate($date)); <br />
        <br />
        If a string doesn't exist in a particular language, then the equivalent 
        in English will automatically be used instead.</li>
    </ul>
    <p><strong>lang/en/help</strong> - contains whole help pages (for popup context-sensitive 
      help)</p>
    <blockquote>
      <p>Main help pages are situated here, while help pages specific to each 
        module are located in subdirectories with the module's name.</p>
      <p>You can insert a helpbutton in a page with the helpbutton function.</p>
      <p>eg helpbutton(&quot;text&quot;, &quot;Click here for help about text&quot;);</p>
      <p>and for modules:</p>
      <p>helpbutton(&quot;forumtypes&quot;, &quot;Forum types&quot;, &quot;forum&quot;);</p>
    </blockquote>
    <p>Note that you can edit languages online, using the administration web tools 
      under &quot;Check this language&quot;. This makes it easy to not to only 
      create new languages but to refine existing ones. If you are starting a 
      new language, please contact me, <a target="_top" href="http://dougiamas.com/">Martin 
      Dougiamas</a>. </p>
    <p>You might also like to post in the <a target="_top" href="http://moodle.org/mod/forum/view.php?id=43">Languages 
      forum on Using Moodle</a>. </p>
    <p>If you are maintaining a language an ongoing basis, I can give you <a href="?file=cvs.html">CVS 
      write access to the Moodle source code</a> so that you can directly maintain 
      the files.</p>
  </blockquote>
  <h3><a name="database" id="database"></a>Database Schemas</h3>
  <blockquote>
    <p>Given a working database with defined tables, the intentionally simple 
      SQL used in Moodle should work fine with a wide variety of database brands.</p>
    <p>A problem exists with <strong>automatically creating</strong> new tables 
      in a database, which is what Moodle tries to do upon initial installation. 
      Because every database is very different, there doesn't yet exist any way 
      to do this in a platform-independent way. To support this automation in 
      each database, schemas can be created that list the required SQL to create 
      Moodle tables in a particular database. These are files in <strong>lib/db</strong> 
      and inside the <strong>db</strong> subdirectory of each module.</p>
    <p>Currently, only MySQL and PostgreSQL are fully supported in this way (no-one 
      wrote the schemas for other brands).</p>
    <p>Moodle 1.2 will use a new method of database-independent XML schemas that 
      will make all this unnecessary.</p>
  </blockquote>
  <p>&nbsp;</p>
  <h3><a name="courseformats" id="courseformats"></a>Course Formats</h3>
  <blockquote>
    <p>Moodle currently supports three different course formats: weekly, topics 
      and social. </p>
    <p>These are a little more connected to the rest of the code (and hence, less 
      &quot;pluggable&quot;) but it is still quite easy to add new ones.</p>
    <p>If you have any ideas for different formats that you need or would like 
      to see, get in touch with me and I'll do my absolute best to have them available 
      in future releases.</p>
  </blockquote>
  <p>&nbsp;</p>
  <h3><a name="doc" id="doc"></a>Documentation and articles</h3>
  <blockquote>
    <p>If you feel like writing a tutorial, an article, an academic paper or anything 
      else about Moodle, please do! </p>
    <p>Put it on the web and make sure you include links to <a target="_top" href="http://moodle.org/">http://moodle.org/</a></p>
  </blockquote>
  <p>&nbsp;</p>
  <h3><a name="bugs" id="bugs"></a>Participating in the bug tracker</h3>
  <blockquote>
    <p>Finally, I would like to invite you to register on the &quot;bug tracker&quot; 
      at <a target="_top" href="http://moodle.org/bugs/">http://moodle.org/bugs</a> 
      so you can file any bugs that you find and perhaps participate in discussing 
      and fixing them. </p>
    <p>&quot;Bugs&quot; not only includes software bugs with current versions 
      of Moodle, but also new ideas, feature requests and even constructive criticism 
      of existing features. The beauty of open source is that anyone can participate 
      in some way and help to create a better product for all of us to enjoy. 
      In this project, your input is very welcome!</p>
  </blockquote>
</blockquote>
<p>&nbsp;</p>
<blockquote> 
  <blockquote> 
    <blockquote> 
      <p align="center">Thanks for using Moodle!<br />
        <br />
        <a target="_top" href="http://dougiamas.com/">Martin Dougiamas</a>, Lead 
        Developer </p>
    </blockquote>
  </blockquote>
</blockquote>
<p>&nbsp;</p>
<blockquote> 
  <p>&nbsp;</p>
</blockquote>
<p align="center"><font size="1"><a href="." target="_top">Moodle Documentation</a></font></p>
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